Method and means for providing refrigeration



June 1 R. w. WATER FILL EI'AL 6,401

METHOD AND MEANS FORPROVIDING REFRIGERATION Fild 001;. s, 1933 4 Shets-Sheet 1 /2 V Fffg= 1- EL H u "'E 13? 23 2?) /6 alllllllllll 3? IIIIIIIIII v I v. "n"... IIIIIIIII IN VEN TOR.

Robert ldldaterf'xll 4 Carlyle ITL/{shley 3 BY Walk A TTORNEY R. w. WATERFILL ETAL 246,401

June 17,1941.

METHOD AND MEANS FOR PROVIDING REFRIGERATION 4 Sheets-Sheet 2 Fil d Oct. 3, 1933 ATTORNEY June 17, 1941. R. w. WATERFILL mm; 2,246,401

ME'iHOb AND MEANS FOR PROVIDING REFRIGERATION Filed Oct. 3, 1935? 4 Sheets-Sheet 5 F15= EI- ii n. 7 I 1;} 46 q 89 gr: w a :w J

4 JNVENTOR. Robert Zclldaierfzll a? Carl: 1e fllflshle FI5" 7- j 9 BY MM A TTORNEY 31 1941- R w. WATERFILL ETAL 6,40l

METHOD AND MEANS FOR PROVIDING REFRIGERATION Filed 001'. 3, 1935 4.Sheets-Sheet 4 INVENTOR.

A TTORNEY Patented June 17, 1941 METHOD AND MEANS roa movrnmo REFRIGERATION Robert w. Water-nil, as Orange, and Carlyle M. Ashley, Maplewood, N. 1., asslgnors, by memo assignments, to Carrier Corporation, Newark,

N. 1., a corporation of Delaware Application October a, 193:, Serial No. 691,928 18 Claims. (01. 62-6) This-invention relates to methods of and.

means for storing refrgeration, and'more particularly to a method for use with an air conditioning system, wherein the refrigerating effect A feature of the invention resides in the use of a relatively small refrigerating machine which is operated for relatively long periods of time, as opposed to present day practice in which a large machine is operated for a short time.

of a relatively small machine is stored during A further feature of the invention resides in low air conditioning load periods, and the storage the use of agsmall refrigerating compressor ,in drawn upon to augment the capacity of the maconjunction with a low temperature evaporator chine during high air conditioning load periods. for freezing ice during low air conditioning load In designing an air conditioning system for periods, and in conjunction with a high tempera- .an enclosur ,it is necessary to estimate the march ture evaporator, for cooling air, either directly, mum heat load to which the buildingwill be or through an intermediary heat transfer mesubiected. While this maximum may be much dium, during high air conditioning'load periods. greater than the average condition, it has here- Another feature of the invention resides in the tofore been necessary to provide refrigeration use of a low temperature evaporator to freeze capacity sufficient to cool the enclosure under ice during low air conditioning load periods, and any extreme condition. In other words, the rethe use of the ice to condense refrigerant vapors frigeration capacity is sufficient to take care of during the high air conditioning load periods. rare peak load conditions, and hence, under Still a further feature of the invention resides ordinary conditions, the capacity is excessive. in the provision of two direct expansion evap- Further, since the heat load is an estimate, not go orators in an air stream, one of which is supa precise calculation, various safety factors are plied with liquid refrigerant from a refrigerating generally included. In this way, the capacity 1 machine, and the other of which is supplied with is further pyramided. When it is remembered liquid refrigerant from an ice storage tank. that the average machine operates only about Still another feature resides in the provision of eight hours per day, it is apparent that the caa coil which is used alternately as a refrigerant pactiy, over and above the other mentioned facevaporator and a refrigerant condenser. tors, is about three times as great as would be Various other objects and features of the innecessary if it could be operated twenty-four vention, making for simplicity, economy, and efhours per day. Consequently, the first cost is flciency, will be more apparent from the descripexcessive. If, as is usual, themachine is elec- 0 tion and accompanying drawings, in which: trically driven, the connected load is, and hence, Fig. 1 is a diagrammatic plan view of a systhe demand (a fixed operating cost), and other tem for air conditioning an enclosure, charges are, unduly great. Fig. 2 is an elevation, in section, of an air it is an object of the invention to provide a conditioning device, embodying one form of apmeans for storing refrigeration during low load plicants invention, which may be used in conperiods, and for drawing upon this storage durnection with the system of Fig. 1, ing high load periods. Fig. 3 is a sectional elevation 0% an enclosure It is another object of this invention to proand a'device for conditioning it, which device vide'an air conditioning system in which the embodies another form of applicants invention, required capacity of the refrigerating machine is. 40 Fig. 4 is a wiring diagram showing the autoreduced far below the capacity of the refrigermatic control of the elements ofFig. 3, ating machines in comparable present day sys- Fig. 5 illustrates an evaporator which may be temg substituted for certain elements of the system A further object'of the invention is to provide of Fig. 3, an air conditioning system in which substantial Fig. 6 is an elevation, partly in section, of savings in first and operating costs are effected. a unit, embodying another form of the invention, Still another object of the invention is to prowhich may be utilized'for cooling the enclosure vide anair conditioning system sufllciently flexof Fig. 3, ible to'overcome errors which occur in the esti- Fig. 'l is a wiring diagram for the unit of Fig. 6, mation of heat load requirements. Fig. 8 is-an elevation, partly in section, of A further object of the invention isto provide an air conditioning unit embodying another varimeans for increasing the peak refrigeration caation of the invention, and pacity of an air conditioning system without Fig. 9 is a wiring diagram for the unit of increasing the refrigerating machine capacity. Fig. 8.

Essentially, this invention contemplates the use, in an air conditioning system, of a refrigerating machine of relatively small capacity in conjunction with two evaporators. One evaporator is used, during off-load periods, for storing refrigeration by freezing ice. The other evaporator is used during on-load periods, either directly or through an intermediary heat transfer medium, for cooling a volume of air. Whenever the air conditioning. load exceeds the capacity of the refrigerating machine, the storage is drawn.

upon to make up the deficiency. The refrigerating machine, obviously, is operated for longer periods of time than is the air conditioning system. While each of the accompanying figures shows two evaporators, it is entirely possible to carry out the invention with only one.

Applicants have found two general ways in which the stored refrigeration may be used to augment the capacity of the machine, to wit,

either cooling liquid, or condensing a portion of the refrigerant vapors. Several variations of each method are illustrated in the drawings.

In the drawings, similar designations referring to similar parts, Fig. 1 shows a simple air conditioning system in which air is withdrawn from an enclosure ill through conduit ll, treated in conditioner l2, attemperated by untreated air through bypass conduit is, and discharged by fan it through conduit I5 back into the en.- closure itl. The conditioner l2 (Fig. 2) comprises a casing l6 divided by a horizontal partition ll into an upper or spray chamber l8, and a lower or freezing-storage chamber iii. A weir 20, in cooperation with a side of the casing l6 and the partition ll forms a well Zl for collecting water from the sprays 22. Any excess water flows over weir Z6 and passes through holes 23 into the freezing chamber iii. A first (high temperature) evaporator 2 located in and adapted to cool the collected water in well 2!, is supplied with a refrigerant, through pipe 25, from the condenser 26 of a refrigerating machine 21. Similarly, a second (low temperature) evaporator 26, located in the freezing chamber i9, is supplied with re- 4 frigerant from condenser 26 through pipe a.

Refrigerant vapor from evaporator M is returned to the compressor of refrigerating machine 21 through pipe 29, while vapor from evaporator 28 is returned through pipe 29a. An expansion valve 30 regulates the admission of refrigerant to evaporator 26in response to variations in superheat in suction line 29, as indicated by thermal element 3|. In this manner, water collecting in well 2! is cooled to any desired point, degrees F. for example.

In a similar manner, the supply of refrigerant to evaporator 28 is controlled by expansion valve 32 responding to variations in superheat as registered by thermal element 33. A stop valve 36, preferably of the quick acting type, opens or closes suction line 29a, preferably in response to variations in the suction pressure as indicated by broken line 35. The valve 34 is so adjusted as to snap open whenever the suction pressure falls below a value corresponding to a temperature of 28 degrees F., and snaps closed whenever the suction pressure rises above a point corresponding to 32 degrees F. A pump 36 withdraws cooled water fromwell 2|, through pipe 31, and discharges this water through spray'heads 22. Air passing through spray chamber l8, under the influence of fan It, contacts with the sprays and is cooled thereby. If, as will be hereinafter explained, the dewpolnt temperature of the air leaving the sprays is above a desired point, 52

degrees F. for example, thermostat 38 operates mixing valve 39, thereby partially closing pipe 3'8 and partially opening pipe 66. As a result, water from chamber is, cooled to approximately 32 degrees F. by ice 5! on evaporator 28, s mixed with water from well 28 which, as was previously stated, is cooled to approximately 45 degrees F. by evaporator 24%. If the resulting mixture is not capable of cooling the air to the desired dewpoint, then thermostat 36 will act to increase the proportion of water withdrawn from chamber l9. Conversely, if the mixture is too cool, thermostat 33 will act to increase the water drawn from well ft. The quantity of water withdrawn from chamber :19 spills over weir 2t and passes through holes 23 back into chamber it.

In operation, assuming that there is no air conditioning load, it is apparent that there is little, or no, heat to be withdrawn from the water in well it. Consequently, the pressure in pipe 29 falls. When the pressure drops to a point corresponding to 28 degrees F., valve 36 opens, thus establishing a circulation of refrigerant through evaporator 28. The refrigerant absorbs heat from the water in chamber I9, and since the refrigerant temperature is below thirty-two degrees F., this water freezes, thereby forming ice on evaporator 28. The formation of ice effects a reduction in suction pressure, as is readily understood. When the pressure drops to a predetermined value, thus indicating that a desired thickness of ice has been built up on evaporator 28, this fall in pressure may be utilized to stop motor 52, by operation of a well known low-pressure cut-off (not shown). If, however, the air conditioning load has increased, thereby causing a rise in suction pressure to a point corresponding to a temperature of 32 degrees F., valve 36 will snap closed, thereby stopping the circulation of refrigerant through evaporator 28, and causing an increased circulation in evaporator 2 3. As the load continues to rise, the entire capacity of machine 2'? will be utilized in holding the temperature of water in well 2! at the desired 45 degrees F. As the load increases above the capacity of machine 21, the temperature of water in well 2| rises above the desired 45 degrees F., and consequently, the dewpoint temperature of air in spray chamber l8 rises. It is at this point that thermostat 38 operates valve 39 in the manner and for the purpose hereinbefore explained, thus drawing upon the stored refrigeration to augment the capacity of machine 27. It is of importance to note that a peak load of any magnitude may be handled in this way.

In the arrangement of Fig. 3, applicants provide a conditioning unit located within the enclosure lll. The unit comprises generally casing 33 having an air inlet opening M near its base, a pair of fans 45, a motor 46 for driving the fans, and two heat transfer coils ll and 48, located in the air stream at a point between the air inlet 66 and fans 45. Cold-water from freezing tank 69 is circulated by pump 50 through inlet pipe 5l, supply pipe 52, coil 4? and return pipe 53. Heat transfer coil 38, a direct expansion evaporator, is supplied with refrigerant from condenser 26 of refrigerating machine 21, through pipe 54. Refrigerant vapors are returned to the compressor of machine 21 through suction line 55. A. suitable expansion valve 56, responding to changes in superheat in suction pipe 55, as indicated by thermal element 51, regulates the admission of refrigerant to coil 48. Freezing tank 49 is provided with an evaporator comprising a number of pipe coils I8, preferably finned to increase the available heat transfer surface, and Joined at their opposite ends by an inlet header and a discharge header 80. Refrigerant from condenser 26 is supplied to inlet header 59 through pipe 544:, andvapors are returned to machine 21 through suction line 55a. The admission of, refrigerant to coils 58 is controlled by an expansion valve 6| responding to changes in super heat as indicated by thermal element 62. Electrically operated solenoid valves 63 and 64 are provided in supply pipes 54 and 54a respectively to open and close these pipes under the control of thermostat 66, located within enclosure III, in a manner and for reasons hereinafter to be made clear. A pressure operated stop valve 65, similar in all respects to valve 34 of Fig. 2, opens suction line 55a whenever the suction pressure falls to a point corresponding to a temperature of 28 degrees F., and closes when the suction pressure rises above 32 degrees F.

It is of importance to note that the air conditioning unit of Fig. 3 is of the off-on type, i. e., fans at maintain a continuous circulation of air within enclosure II), but the heat transfer coils operate intermittently in response to temperature changes within the enclosure as indicated by thermostat 66.

Considering the operation of the unit (Figs. 3 and 4), fans 45 are placed in operation by closing hand switch t1, thus completing the electrical circuit including motor 46. The refrigeration machine is started by the closing of hand switch it, thus completing the electrical circuit including high pressure cut-out- 69, low pressure cut-out Ill, and compressor motor 42. Hand switch ll is closed to m ake contact at it. Assuming that enclosure I0 requires cooling (above 75 degrees F., for example), arm ll of thermostat it will make contact at it, thus completing the electrical circuit including switch ii, contacts "it, thermostatic arm lit, contact it, solenoid valve d3,and pump till. As a result, valve it is opened against the tension of a spring, and pump it starts a circulation of water through coil ii. The opening oi til admits refrigerant to coil dd. Air in taken through it, by fans at, gives up its heat to coil iii. Any heat in excess of the capacity oi coil til is absorbed by water circulating in coil t'l. if the air conditioning load is light, coil 48 does all. of the work; if heavy, coil 41 makes up the valve t l. as a result, valve 84 opens, prefer-' ing the late evening, night, and early morning,

for example, hand switch ll may be moved to upon low pressure cut-out will break the circult to stop compressor motor 42.

If, as might occur during a continuous high peak load, all'of the ice in tank 49 were melted. the entire loadwould be placed upon coil 48. Since the capacity of the machine is designedly less than this peak load, the pressure in the coil 48 would rise, and consequently, the pressure in condenser 26 would rise. To prevent the creation of a dangerously high pressure, a high pressure cut-out 69 of well known construction, is placed in the circuit to stop motor 42 whenever the condenser pressure attains a predetermined maximum. f

In certain cases, particularly those involving the renovation of existing systems, it, is desirable to eliminate the direct expansion evaporator 48.

To this end, applicants contemplate the insertion of an evaporator 11, of shell and tube construction, for example, in the return pipe 53. All other elements may be just as illustrated in Fig. 3. Refrigerant is supplied to H and vapors are returned to machine 2'! through pipes 54 and 55' in exactly the same manner as was previously described in connection with Fig. 3; and likewise, the control may be identical. In operation, whenever enclosure it requires cooling, water returning from coil M is primarily cooled by evaporator ii. If the load is greater than the capacity of the machine, the deficiency is made up by the melting of ice in freezing tank 49.

In each of the systems hereinbelore described it is oi note that the capacity oi the relrigerab.

ing machine lili' is augmentedby melting ice to cool a liquid which is thereafter circulated through the air conditioning system. Hence, each of these arrahgements'iequires the use or a pump. In Fig. 6, applicants illustrate a unit ior conditioning enclosure iii in which the storage edect is utilized in a slightly different way, thereby to eliminate the use of a pump. tlienerally, the unit comprises a casing it having an upper chamber in which the air conditioning and reirigeration storage elements are located, and a lower chamber for housing a suitable refrigeration machine ill.

deficiency. Thermostatrtii, preferably, is of the quiclnacting type, i. e., arm i3 moves from one extreme position (contact it) to the other ex- Fan dd, mounted at the top of the unit, draws air through inlet it, over the high temperature evaporator it, over the low temperature evaporator M, and discharges the air into enclosure ably against'the tension of an associated spring,

it, Evaporator it is suppliedwith refrigerant irom condenser it through pipe ti under the regulation at eitpansion valve til responding to changes in super-heat in suction line at, as indi cated by a thermal element t t. 'ltreeaing tank It is provided with pipe coils tit, preierably or finned construction, joined at their opposite ends by an inlet header ti and a. discharge header M. Reirigerant irom condenser it is supplied to header ti through'pipe tin, and vapor is returned to machine ill through suction pipe the. Electrical solenoid valves it and at open and close lines ti and did respectively in response to changes in temperature in enclosure it, as indicated by a thermostat it in the enclosure to be conditioned. ll. valve ti (similar in all respects to valve 34 of Fig. 2) opens and closes suction pipe "at in accordance with changes in suction pressure. Evaporator is supplied with refrigerant from header 08 through pipe 02. Vapor is returned from 80 to header 0')! through pipe 93.

Considering the operation of the unit, fans 35 are started by closing hand switch 8?, thus completing an electrical circuit including fan motor 48. The closing of hand switch t8 completes a circuit including highpressure cut-out 053, low pressure cut-out it and compressor motor 32. Thermostat 85 of Fig. 7 is identical with thermostat 68 of Figs. 3 and 4. Assuming that enclosure I0 does not require cooling, thermostatic arm 13 will be making contact at it. Closing of hand switch 9% will, therefore, complete an electrical circuit including arm l3, contact l5, and solenoid valve 90. As a result, valve 0a is opened, preferably against the tension of a spring, to admit refrigerant to receiver til) and header 8i, hence coils 86. Valve ti will open under the influence of a suction pressure corresponding to 28 degrees F., thereby establishing refrigerant circulation through coils lit. Consequently, a coating of ice will be formed in coils It. When the coating is of a. desired thickness, as indicated by a reduced suction pressure, low

pressure cut-oil 50 will open the electrical circuit including compressor motor 42, thus stopping machine 21.

Assuming that the temperature of the enclosure has increased to a predetermined point, 75 degrees F. for example, thermostatic arm will break the electrical circuit at 15. Valve 80 will immediately close under the tension of its associated spring. Simultaneously, since thermostat 80 is of the quick acting type, arm 73 will make contact at H, thus completing a circuit including solenoid valve 89. As a result, valve 00 opens against the tension of an associated spring, to admit refrigerant to evaporator 19. Refrigerant vapor pressure in the suction line 03 will immediately rise, thereby closing valve 0i (closed above 32 degrees F.), and simultaneously,

allowing low pressure cut-out 10 to close the circult including compressor motor 42, hence start ing machine 21. Circulation of refrigerant through 19 accomplishes a cooling of air passing thereover.

It is apparent that the closing of solenoid valve 00. and pressure valve 0|, traps a volume of refrigerant in coils 06;and a volume of liquid in receiver 8Ib. Any vapor will, of course, be condensed by ice on the coils. The liquid in receiver 0lb will be evaporated by absorbing heat from the air passing thereover; and the resulting vapor will pass into coils 86, there to be condensed. The condensate flows, by gravity, from header 08, through pipe 92 into evaporator 00. Air passing over 80 will give up its heat causing refrigerant in the evaporator to boil.. The resulting vapors will pass through pipe 93 into header 81, thence into coils 06, where they condense by giving up heat to the surrounding ice. Thequantity of refrigerant-evaporated in 80 will vary as the difference between the capacity of machine 21 and the air conditioning load varies. In this way, the stored refrigeration is utilized to augment the capacity of machine 2'I High pressure cut-out 60 functions, Just as in Figs. 3 and 4, to cut-oi! machine 21 whenever the condenser pressure rises above a desired point.

In Fig. 8, applicants illustrate another system operating upon the principles disclosed in connection with Fig. 6. The air conditioning unit comprises generally a casing 43 having an air inlet ll near the base thereof, fans 45. fan motor t8, and an evaporator coil 90 located-in the casing between the inlet opening and the fans. Coil is supplied with refrigerant from condenser 25 of machine 27 through pipe 96 under the regulation of expansion valve 9'! responding to changes in superheat in suction pipe 98 as indicated by a thermal element 99. Solenoid valve Hi0 opens and closes line 96 under the control of a' thermostat b6 responding to temperature changes in enclosure 50.

A freezing tank IOI, located above evaporator 95, is provided with finned coils i02-joined at their opposite ends by an inlet header I00 and a discharge header lu l. Refrigerant from condenser 2a is supplied to inlet header B03, hence, coils M2, by pipe 96a, and vapors are returned to machine 27 from discharge header tilt through trap E05 and suction pipe 00a. A suitable expansion valve I06 regulates the admission of refrigerant under the control of thermal element i0? responding to changes in superheat in suction line a. Solenoid valve H0 opens and closes pipe 96a under the control of thermostat 66 in enclosure i0. Pipe I08. provided with a trap I09 joins inlet header I03 and suction pipe 98a. Pipe III connects discharge header I04 to pipe 96 between coil and expansion valve 91.

Considering Figs. 8 and 9, fans 65 are placed in operation by closing hand switch 61, thus completing an electrical circuit including motor 46. Closing of hand switch 68 completes a circuit including high pressure cut-out 69, low pressure cut-out I0, and compressor motor 42, thereby starting machine 21. Assuming that enclosure i0 does not require cooling, arm I3, of quickacting thermostat 86 will be making contact at 15. Therefore, closing of hand switch II at contact I2 will complete a circuit includingarm 13, contact 15 and solenoid valve IIO. Valve IIO opens against the tension of an associated spring to admit refrigerant to coils I02. The resulting refrigerant circulation will cause the formation of a coating of ice on coils I02. Assuming that enclosure I0 is now calling for cooling, thermostatic arm 73 will break the circuit at 15, hence valve Ii0 will close under the tension of its spring. Simultaneously, arm 13 will make contact at It to complete a circuit including valve I00. The opening of valve I00 admits refrigerant coil 95, thereby cooling air passing through casing 43. Any refrigerant trapped in I02 will be condensed by the melting of ice. Whenever the air conditioning load exceeds the capacity of machine 21, this refrigerant from I02 flows by gravity from header I04 through III and into coil 95, thus making up the deficiency of machine 21. Machine 21 takes its full vapor capacity through line 08, and the excessv vapor, corresponding to liquid admitted from I, passes upward through pipes 00a, I08, trap I09, and into coils I02, wherein it is again condensed.

Whenever cooling is not required, as during the night, hand switch II may be moved to break the circuit at I2, thus closing valve I00,

and to make a circuit at 16, thereby opening valve H0. Opening of H0 starts the formation of ice on I02 as previously described. Low pressure cut-out 80, just as was explained in connection with Figs. 2-7, may be set to stop motor 42 when a sufliciently thick ice coating has been formed. Likewise. as was previously described, high pressure cut-out 09 protects the system by stopping machine 2'! whenever the condenser pressure reaches a predetermined value.

Since certain changes may be made in the an air conditioning system having a varying heat load which comprises evaporating a refrigerant from a cenral source of supply at relatively low temperatures to freeze water during low air conditioning load periods, evaporating a refrigerant from the same source at relatively high temperatures to cool air during high air conditioning load periods, and melting the ice to augment the refrigerating effect secured by said high temperature refrigerant evaporation.

2. In an apparatus for cooling the atmosphere of an enclosure having a varying heat load, a refrigerating machine having a relatively small capacity, a refrigerant circuit including an evaporator normally receiving refrigerant supplied to serve said second refrigerant circuit when the": suction pressure falls below a predetermined point and for cutting off the supply of refrigerant to said second refrigerant circuit when the suction pressure rises above a predetermined point.

3. In an apparatus for cooling the atmosphere of an enclosure, a first refrigerant circuit including an evaporator normally receiving refrigerant supplied thereto at a relatively high suction pressure, a second refrigerant circuit including d. In a conditioning system, a conditioning I unit including air cooling means, an ice freezing chamber, means for supplying water from said freezing chamber to said air cooling means, means for returning water from said cooling means to said freezing chamber, and means including a refrigerant evaporator for cooling said water prior to its return to said freezing chamher during periods of high air conditioning heat load.

,5. In an air conditioning system for an enclosure having a varying heat load, a first 'air cooling evaporator, a second air cooling evaporator, an ice, freezing chamber, heat transfer coils in said chamber, a refrigerating machine, means for supplying refrigerant from said machine to said heat transfer coils during low air conditioning load periods, means for supplying refrigerant from said machine to said first air cooling evaporator during high air conditioning load periods, and means for supplying refrigerant from said heat transfer coils to said second air cooling evaporator during high air conditioning load periods.

6. The method of providing refrigeration-for an air conditioning system having a varying heat load which comprises evaporating in a first ergpansion coil a refrigerant at relatively low temperatures to freeze ice during low air conditioning load periods, evaporating in a second expansion coil a refrigerant at relatively high temperatures to cool water during high air conditioning load periods, and melting the ice to provide an additional source of cooled water.

7. The method of providing refrigeration for an air conditioning system having a varying heat load which comprises evaporating a refrigerant in one cooling coil at relatively low temperatures to freeze water during low air conditioning load periods, evaporating a refrigerant in a second separately fed cooling coil at relatively high temperatures to cool water during high air conditioning load periods, and further cooling the water during high air conditioning load periods by melting the ice.

8. The method of providing refrigeration for an air conditioning system having a varying heat load which comprises evaporatinga refrigerant at relatively low temperatures to freeze ice during low air conditioning load periods, evaporating a refrigerant at relatively hightemperatures to cool air, and melting said ice during high air conditioning periods to condense a porton of the refrigerant evaporated-to cool the air.

9. The method of absorbing heat from a source having a widely varying load factor which comprises evaporating a refrigerant to freeze a liquid during low heat load periods, evaporating a refrigerant at a temperature greater than the freezing temperature of said liquid by absorbing heat from said source during high heat load periods, and melting the frozen liquid to augment the heat absorption secured by the second evaporation step.

10. The method of providing refrigeration for absorbing heat from a source having a widely varying heat load factor which comprises evapo rating a refrigerant in a first circuit to freeze a liquid during low heat load periods, evaporating refrigerant of the same character in a second cir- "cult at a temperature greater than the freezing 5 temperature of said liquid to absorb heat during high heat load periods, and melting the frozen liquid to augment the cooling effect secured by refrigerant evaporation in the second circuit, saidv first and second circuits being in parallel arrangement.

11. The method of absorbing heat from a source having a widely varying load factor which comprises evaporating a refrigerant in a first circuit to freeze ice during low heat load periods, evaporating a refrigerant in a second refrigerant circuit to cool water during high heat load periods, melting the ice during high air conditioning load periods, mixing the resulting cold water with the water cooled by evaporation of refrigerant in the second refrigerant circuit, and utilizing the mixture to absorb heat from the source.

12. The method of providing refrigeration for an air conditioning system having a varying heat load which comprises evaporating at a relatively 5 low temperature a refrigerant from a central source of supply to store up refrigeration effect during low air conditioning load periods, evaporating at a relatively high temperature refrigerant from the same source during high air condi- 7o tioning load periods to cool air, and drawing upon the stored refrigeration to assist in cooling said air during high air conditioning load periods. 13. In an apparatus for cooling the atmosphere of an enclosure having a varying heat load, a con- 7d ditioning unit, air cooling means in said unit, a

storage tank in which water is adapted to be frozen, means separate from the air cooling means for cooling water in said ice storage tank below the freezing point, means including a refrigerating machine of lesser capacity than the capacity of said conditioning unit for supplying refrigeration during high air conditioning loadperiods to said air cooling means only, and means operative responsive to a drop in suction pressure below a predetermined point for supplying refrigeration, during low air conditioning load periods, to said water cooling means in said tank, and means for utilizing the water from said tank to augment the capacity of said air cooling means.

14. In an air conditioning system having a varying heat load, a first evaporator normally receiving refrigerant supplied thereto at a relatively high suction pressure, a second evaporator for freezing water normally receiving refrigerant supplied thereto at a relatively low suction pressure, means for supplying refrigerant to said first evaporator during high air conditioning load periods and means operative when the suction pressure is below a predetermined point for supplying refrigerant to said second evaporator during low air conditioning load periods, and means for utilizing the refrigerating eflect of said frozen water to augment the cooling capacity of said first evaporator.

15. In an air conditioning system, a freezing chamber, means for freezing water in said freezing chamber during low air conditioning load periods, a water cooling chamber, means for cooling water in said cooling chamber during high air conditioning load periods, and means for melting the ice in said freezing chamber to augment the capacity of the cooling means in said water cooling chamber.

16. The method of providing refrigeration for an air conditioning system having a varying heat peak.

aerator tion to assist in cooling said air during high air I conditioning load periods.

17. In combination, a compartment to be cooled, a refrigerant liquefying unit, means for operating said unit, a refrigerant evaporator in refrigerant flow relationship with said unit and having means for cooling air for said compartment, a holdover tank, holdover in said tank, an evaporator in thermal exchange relationship with said holdover and in refrigerant flow relationship with said unit, and means for circulating holdover from said tank in thermal exchange with air for said compartment.

18. In an air conditioning system for an en closure having a varying heat load an air cooling apparatus containing an air cooling evaporator, a freezing tank, a water freezing evaporator in said freezing tank, a refrigerating machine,

means for supplying refrigerant from said ma-.

chine to said water freezing evaporator during low air conditioning load periods, means for supplying refrigerant from said machine to said air'cooling evaporator during high air' conditioning load periods, and means for supplying cold water from said freezing tank to augment the refrigerating effect of said air cooling evaporator during high air conditioning load periods when the load in the enclosure exceeds a predetermined ROBERT W. WATERFILL. CARLYLE M. ASHLEY. 

